lumbricals (lumbrical muscles) of hand

Definition: four intrinsic muscles of the palm; origin, the two lateral: from the radial side of the tendons of the flexor digitorum profundus going to the index and middle fingers; the two medial: from the adjacent sides of the second and third, and third and fourth tendons; insertion, radial side of extensor tendon on dorsum of each of the four fingers; action, flexes metacarpophalangeal joint and extends the proximal and distal interphalangeal joint; nerve supply, the two radial muscles by the median, the two ulnar muscles by the ulnar.